Ooof, 2500 is intense!
When I first started on the journey, I got started with WaniKani, then I got distracted by something shiny and didn’t come back for a year or so. At only level 3 in WaniKani, I came back to a few hundred reviews, and felt completely lost, so I just reset my progress and started over. Since that time, I’ve met with a few distractions and restarted the journey a couple times, but this time it’s feeling real for me. I just recently hit the point where I have done more reviews in the last 6 months than I had for all 5 previous years combined in WK, not to mention starting Bunpro as well to start learning grammar in addition to vocab.
Not quite the same as your struggles with the switch to fill-in, but in a similar vein, the thing that I had done at the beginning that kept causing me trouble later on was giving up too quickly when trying to recall an answer. I’d get the prompt, try to think about the answer for 10 seconds or less, and then give up and reveal the answer. More recently, I’ve been trying to give myself a minute or so to recall something if I feel like it’s right on the tip of my tongue, and that has been feeling much more rewarding or effective when I get it right. If I got it wrong but still felt like I was close, then I would wait for it to come back around and try a second guess before revealing the answer, which is also something that I had never previously done. I have found that probably less than 25% of the time, I get the answer on the second try, but even just trying to think hard about it has been motivating in its own way… It shows me very clearly which ones I don’t know as well as I think that I do.